Safety and arming mechanism for fuze



May 12, 1970 T. GEFFNER 3,511,183

' I SAFETY AND ARMING MECHANISM FOR FUZE Filed March 6. 1968 4 Sheets-Sheet 1 INVENTOR. TED GEFFNER JOHN P. CHANDLER H IS ATTORNEY.

May 12, 1 970 T. GEFFNER SAFETY AND ARMING MECHANISM FOR FUZE 4 Sheets-Sheet 2 Filed March 6, 1968 FIG. 4

FIG. 5

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INVENTOR. TED GEFFNER JOHN P. CHANDLER HIS ATTORNEY.

4 Y1 h '0 T. GEFFNER 3,511,183

I SAFETY AND ARMING MECHANISM FOR FUZE Filed March 6, 1968 4 Sheets-Sheet 5 FIG. 6

INVENTOR.

TED GEFFNER JOHN P. CHANDLER HIS ATTORNEY.

'MayWIZ; 1970 1'. GEFFNER SAFETY AND ARMING MECHANISM FOR FUZE 4 Sheets-Sheet 4 Filed Maroh 6, 1968 INVENTOR.

TED GEFFNER JOHN P. CHANDLER HIS ATTORNEY.

United States Patent 3,511,183 SAFETY AND ARMING MECHANISM FOR FUZE Ted Gelfner, 48 Park Ave., East Merrick, N.Y. Filed Mar. 6, 1968, Ser. No. 711,123 Int. Cl. F42c 15/00, 15/40, 19/12 US. Cl; 1112-70-2 1 12 Claims ABSTRACT OF THE DISCLOSURE tions. In the cylinder is a piston, a sleeve slidable in the. bore, a barrel between the piston and sleeve with its forward end engaging said shoulder, and ball detent means between the piston, barrel and sleeve. Explosive means operate against the inner ends of the sleeve and cylinder to drive the sleeve forwardly, followed by release of the detent means and then driving the piston. When used as a safety and arming mechanism, forward end .of the piston has a transverse opening and a detonator in the opening which, in starting position, is radially out of line with the booster. The cylinder has an opening aligned with the booster to detonate the same when the piston moves forwardly to position the detonator in line with the booster.

This invention relates to an explosively actuated valve of general utility which can be embodied into a valve which is normally closed or normally open. In a modified formthe valve can be used in connection with a fuze in a novel arming device for actuating a detonator for an explosive charge in a bomb.

An important object of the invention is to provide an improved arrangement for a train of explosives which fire the bomb and which is simpler and safer in construction than existing devices and is confined within an envelope smaller than conventional ones.

A safety and arming mechanism should move the detonator, from a safe or block position to a location directly in line with the booster explosive, which is housed in the main piston of the device. This main piston is positively locked first in safe position and is later locked in line position by a ball detent means, the locking being efiected by a series of spring urged balls which operate on the piston. The main piston is moved fromlocked position to a second position, effecting unlocking of the balls, by energy released from a driving squib either by electrical or by impact means. On explosion of the latter the first burst of energy moves a sleeve supporting the piston to unlocked position and the remaining energy drives the piston to in line position. Pressure between the forward end of the sleeve and the breach is quickly equalized and a spring returns the sleeve to starting position. The ball detent now locks the. main piston in line, i.e., the detonator is directly in line with the booster thus completing the explosive train.

The present invention is novel in that it provides severaldistinct safety features. First, when the detonator is in. the out-of-line position, it is shorted out, which prevents premature firing. In this connection, the leads from the detonatorare attached to two contacts on one side of the main piston and both contacts engage a single conductor strip in the cylinder or housing. When the main piston is moved to the in line position, one button retains contact with the strip while the other button makes a new contact. The new contact and the strip can now complete a circuit to the detonator. The fire pulse circuit may then be closed.

A second safety feature of this mechanism is in a safing switch, which switch is normally open or can be normally closed. When the main piston is moved to the in line position the forward end closes the switch.

A safety pin arrangement is a third safety device. For ground handling and transportation, this means of safety indicates that the detonator cannot be in the in line or armed position. The safing pin with a red flag on the opposite end is inserted through the fuze shell and through the safety and arming mechanism. If the pin cannot be placed in the mechanism, it gives visual indication that the fuze is armed. When the pin is inserted, it mechanically assures a non-armed condition. The pin prevents the movement of the main piston from out of line to in line.

A fourth safety means is a component combining a lanyard, safing pin and battery initiator. This part is self-contained in the safety and arming device. The component is inserted through the housing and main piston making it a shear pin. The forward end of the pin is the battery initiator. This is pointed with a cupping arrangement which houses a spring which preloads the point forward. At the opposite end of this pin is the lanyard ring. At a point forward of the mid-section of the length that is passing through the housing is an undercut which is so constructed that a pre-set tension, generally about 30 pounds pull on the lanyard will fracture the pin. Upon fracturing the forward end or battery initiator, due to the spring preload, will pull that portion of the pin out of the housing and strike the battery commencing its action. The lanyard will pull its portion of the pin out of the housing. Both portions removed from the housing have now freed the main piston. The safety and arming mechanism may now complete the explosive train by moving the main piston to a location that places the detonator in line with the booster.

In the drawings:

FIG. 1 is a central section taken through a normally open valve of the present invention with the parts in prefire position;

FIG. 2 shows the position of the parts in transition after fire;

FIG. 3 shows the parts in final position;

FIG. 4 is a central section of the mechanism of the present invention applied to a safety and arming device for a fuse for a bomb, the parts being shown in prefire position;

FIG. 5 shows the position of the parts in transition after firing;

FIG. 6 shows the spent position;

FIG. 7 shows the shear pin and battery initiator before firing;

FIG. 8 shows the pin after fracturing.

The explosively actuated slide valve of the present invention is illustrated in FIGS. 1 to 3 in connection with a valve structure which is normally closed and it includes a cylinder 10 with a bore 11 having at its forward end a reduced section 12 forming a shoulder 14. This forward end is closed by a fixed wall 16 having a vent hole 18 to relieve the pressure when the charge is spent. The rear of the bore has a thread section 19 which receives a cap 20 containing a squib or cartridge (not shown). Electric leads 21 extend to a source of current (not shown) to fire the squib.

A piston 22 is supported for sliding movement in a barrel 24 having a flange 26 at its forward end which engages shoulder 14, preventing forward movement of the'barrel. A sleeve 27 supports the barrel and the sleeve has limited sliding movement in the bore 11. The sleeve has a shoulder 28 which engages one end of a coiled spring 29, the other end of the spring engaging flange 26.

The wall of the barrel has two through holes 30 receiving balls 31 and when the parts are in pre-fire position (FIG. 1) the inner sections of the balls are seated in an annular groove 32 in the piston. This forms two ball detent stops, locking the piston against forward movement since the inner annular face 34 of the sleeve prevents the balls from moving radially outwardly when in this position. The sleeve has an annular groove 36 to the rear of holes 30 when in the pre-fire position and the piston has an annular groove 37 still further to the rear.

When the squib is fired, the explosive charge acting on the rear annular face 35 of the sleeve, moves the latter forwardly, compressing the spring 29, and lines up annular groove 36 with through holes 30 so the balls are forced outwardly and the piston is now free for forward travel under the influence of the explosive charge acting against piston face 39.

The piston has an enlarged forward section 40 received in sliding relation in reduced bore section 12. The piston and bore 12 have annular recesses 42 and 44 to receive O-rings 46 for sealing purposes.

The enlarged forward piston section 40 has an internal chamber 48 and an inlet opening 49 on one side communicating with an inlet port 50 in the cylinder. An outlet port 51 on the opposite side is closed by the cylinder wall. When the piston has moved full forward outlet port 51 is aligned with an outlet port 52 in the cylinder thus causing the valve to be fully open. Ports 50 and 52 have conduits 54 and 56 connected therewith.

As earlier stated, firing the squib drives sleeve 27 first and then piston 22. Both would move simultaneously except that the detent restrains the piston. Sleeve 27 stops when it contacts shoulder 14 as shown in the first position of FIG. 2. As soon as piston 22 has moved forward to its stop, spring 29 returns the sleeve to starting position. When the piston reaches its full forward position of FIG. 3 all ports are open. The halls are now free to move radially inwardly into blind holes 37 and hold the piston in this forward, open position. It will be appreciated that by changing the location of the cylinder outlet port 52 the structure may be made into a normally open valve. The arrangement can also be modified to make the structure into a poppet valve instead of the sleeve valve.

The apparatus of the present invention as applied to a safety and arming device for a fuze includes a square cylinder 60 having a round bore 61 extending inwardly from its inner end and having a short threaded section '62 which receives the threaded cap 64 which contains a driving squib having an explosive charge (not shown) with wires 66 leading to an electrical source for firing the charge.

The bore has a reduced section 68 at the forward end 73 of the square cylinder (FIGS. 7 and 8). This reduced bore section forms an internal shoulder or seat 69 which limits inward movement of a flange 70 at the inner end of a barrel 71 carried within the cylinder. The barrel is supported by a sleeve 72 received in snug fit sliding relation in bore '61 of the cylinder and having an external annular shoulder 74. A spring 76 acts against this shoulder at one end and against flange 70 at its other end which keeps the barrel 71 firmly against seat 69. The sleeve further has, at its inner end, a diagonal, annular face 77.

A piston 78 moves freely in barrel 71 and its inner end has a concave face 79 against which the explosion of the charge reacts. The piston has annular recesses 80 and 81 which in cross-section form arcs of less than half a circle. The barrel has two oppositely disposed holes 82 in its side wall which receives balls 84 and in the prefire position of FIG. 4 when all the parts are at rest the inner sections of the balls are positioned in the second annular recess 81 and the outer sections are located in holes 82. Their outward travel is limited by the inner surface of sleeve 72.

The lesser diameter section 68 of the cylinder bore is square andextends forwardly to an end.-wall.88. The piston has an enlarged square section 89 freely movable in this latter bore section and has a round transverse bore 90 which receives the detonator 91. Contact buttons 92 and '94 carried by piston section 89 are connected with the detonator 91 to fire the same when current is applied thereto. In pre-fire position (FIG. 4) both contacts engage a conductive plate 96 whichis mounted-at the inner end of a conductive pin 97 and which shorts the contacts. When, however, the piston moves forwardly to its maximum position contact 94 leaves conductive plate 96 and engages a second conductive plate 98 mounted on pin 99 so that when current is applied to pins 97 and 99, the detonator will be fired. The shorting plate is the first safety device earlier mentioned. It will also be apparent that when sleeve 72 first moves forwardly the balls 84 are then cammed radially outwardly by the curved annular recess 81 and the outer sections of the ball reside in annular enlarged section 85 of the bore in sleeve 72.

The forward end wall of the cylinder has an opening 100 through which a forward projection 101 of the piston passes when the piston has been fired. The circuit for the detonator includes another normally open switch comprising spaced contact members 102 and 103 mounted outside the forward end wall 88 of the cylinder. When the piston moves forwardly the projection 101 brings the contacts together (FIG. 6). This is the second safety device.

The third safety device is a pin 104 which, when the piston is in the pre-fire position of FIG. 4, can pass through aligned holes 105- in opposed wall of the cylinder and hole 107 in the forward projection 101 of the piston.

. A red flag attached at the free end of pin 104 when all the way in, tells the operator that the bomb is not armed. If the pin with the red flag is missing, however, and he tries, without success, to insert a pin, he knows that the bomb may be in the armed position of FIG. 6.

The fourth safety device is a safing pin 106 which is positioned in aligned holes 108 and 109 in the squares cylinder section 73 and the square piston section 89.

A lanyard 112 attached by a cable (not shown) to the craft passes through a terminal fitting 114 carried on the pin and the other end of pin 106 carries a battery initiator 116 formed with a point 118 which is spring loaded by spring 119. The pin has an undercut 120 of such depth as to cause the two parts to separate when a pull of predetermined magnitude is exerted on the lanyard, for example 30 pounds. So long as the pin is not fractured, it restrains all movement of the piston in the cylinder. When, however, the pin is fractured the section with the ring is pulled from the aligned holes and the other section moves forwardly under the influence of spring 119. The piston is no longer restrained and the point penetrates the fuse 122 of a thermal battery 124, thus initiating the voltage necessary for firing the detonator.

While there have been described herein what are at present considered preferred embodiments of the invention, it will be obvious to those skilled in the art that many modifications and changes may be made therein without departing from the essence of the invention. It is therefore to be understood that the exemplary embodiments are illustrative and not restrictive of the invention, the scope of which is defined in the appended claims, and that all modifications that come within the meaning and range of equivalency of the claims are intended to be included therein.

I claim:

1. A safety and arming mechanism for a bomb provided with a booster charge, and an electrically actuated detonatorincluding a circuit and a source of electricity for the detonator charge, the mechanism comprising a cylinder having a longitudinal bore extending from its inner end and formed at its outer end with a smaller section, forming a shoulder therebetween, a piston in the cylinder, a sleeve slidable in the bore, a barrel between the piston and sleeve with its forward end engaging said shoulder, and ball detent means between the piston, barrel and sleeve,.explosive means operable on the inner ends of the sleeve and cylinder to drive the sleeve forwardly, followed by release of the detent means and then driving the piston, the forward end of the piston in the reduced forward section of the bore having a transverse opening and a detonator in the opening, which, in pre-fire position is radially out of line with the booster, the cylinder having an opening aligned with the booster to detonate the same when the piston moves full forwardly to position the detonator in line with the booster, means to fire the detonator when in such position, and safety means to prevent untimely firing of the detonator.

2. The structure as defined in claim 1 wherein the ball detent means include balls which lock the piston to the barrel until the sleeve has moved forwardly releasing the balls.

3. The structure as defined in claim 2 wherein a spring returns the sleeve to starting position.

4. The structure as defined in claim 3 wherein the balls lock the piston in fonward position after the sleeve is returned to starting position.

5. The structure as defined in claim 1 wherein a squib actuated by electrical means is the explosive means.

6. The structure as defined in claim 1 wherein a squib actuated by impact means is the explosive means.

7. The structure as defined in claim 2 wherein the barrel has opposed side wall openings receiving the balls and the piston has annular recesses into which the balls partially pass, restrained against outward movement by the sleeve.

8. The structure as defined in claim 1 wherein the cylinder is made from insulating material.

9. The structure as defined in claim 1 wherein a shorting plate is positioned in the forward section of the cylinder bore and contacts from the detonator engage said plate when in pre-fire position, preventing premature firing.

10. The structure as defined in claim 1 wherein a switch with normally spaced contacts is in series with the detonator circuit and is closed by impact of the piston when it reaches full forward position.

11. The structure as defined in claim 1 wherein the cylinder and piston have holes aligned when in pre-fire position and a pin is positioned in said holes to indicate an unarmed position.

12. The structure as defined in claim 1 wherein the cylinder and piston have a second set of holes aligned when in pre-fire position and a frangible pin passing through said holes restrains movement of the piston until the pin is broken by a tension pull and removed from the cylinder hole.

References Cited UNITED STATES PATENTS 2,737,890 3/1956 Brode 102-702 2,931,874 4/1960 Leaman l02--70.2 2,996,990 8/ 1961 Leaman 10270.2 2,796,074 6/1957 Daudelin 137-68 2,777,455 1/ 1957 Daudelin 137-68 BENJAMIN A. BORCHELT, Primary Examiner T. H. WEBB, Assistant Examiner U.S. Cl. X.R. 13768 

